1. Field of the Invention
This invention relates to the electrolytic recovery of metals and more particularly it concerns novel methods and apparatus for monitoring and regulating current in an electrolytic bath.
2. Description of the Prior Art
U.S. Pat. Nos. 3,418,225, 3,450,622, 3,463,711, 3,551,318 and 3,616,435 all relate to the recovery of silver from used photographic or X-ray plates. In the systems described in those patents silver bearing material is dissolved off from a film plate as it passes through a solution; and then the silver is recovered by subjecting the solution to electrolytic action so that the silver plates out onto a removeable electrode. Various arrangements are provided for control of the electrical current through these solutions, including means for maintaining current flow for given lengths of time corresponding to the size and number of film plates passing through the solution. Means are also provided for manually adjusting the magnitude of current flow.
In U.S. Pat No. 3,067,123 there are shown, in an electrolytic bath, a pair of probe electrodes which sense the current flow in an electrolytic bath and feed back a signal to drive a potentiometer so that the current flow is maintained at a constant or fixed value.
None of the prior art provides any capability for maintaining a continuous flow of current through an electrolytic bath and adjusting the magnitude of this current to coincide with changes in metal concentration in the bath as more metal is added to the solution and as more metal is plated out from solution.